In this study, we used both NIRIM type and end-launch type microwave plasma CVD apparatus to deposit diamond from gas phase. Our target is to develop the deposition process to fabricate the heteroepitaxial growth of diamond on large Si substrate. For this target, we have investigated the diamond nucleation phenomena, and tried to find out the nucleation control method.At first, using NIRIM-type apparatus, high supersaturation during the initial stage of deposition enhanced the nucleation density on Si substrate by two orders of magnitude. This effect might be dependent on substrate species due to the chemical affinity between carbon atom and substrate element.Using high supersaturation method, we can successfully deposit flat diamond film on BN interlayer at the highest nucleation density 10ィイD110ィエD1cmィイD1-2ィエD1. However, the surface roughened according to deposition time. Therefore, in order to fabricate the flat film, it is necessary to arrange the crystal orientation of nuclei at i
… Morenitial growth and control the growth orientation by deposition conditions.Next, we developed the end-launch type apparatus, which consisted of Φ120-deposition chamber and Φ100-substrate holder. Using developed apparatus, we can successfully deposit diamond on no-treated Si substrate with high nucleation density by high supersaturation method. Therefore, we confirmed the possibility to deposit diamond film on the whole Φ100-substrate by optimizing the deposition condition.We also tried to arrange the crystal orientation of initial nuclei by the supersaturation method with substrate bias. The enhanced effect of nucleation density was higher by using both the supersaturation and the bias during the initial stage of deposition. We could successfully deposit the epitaxial diamond on Si substrate, although the epitaxial area was limited to small area in substrate.The whole results of this study means that the optimization of deposition conditions make the epitaxial growth of diamond on large Si substrate possible. Less